There is a great variety available, probably greater than when you were last active. I found the same thing, when I got back in, even though that is now almost 20 years ago. I went from the age of Monogram and Revell kits, with figures in a kit as a general rule, to the world of figureless kits and aftermarket makers.
There are some manufacturers of figures, who have their own sites. CMK is one. But you'll find that there are online shops that carry many different brands.
MiniArt might be a good brand to look into. They produce sets of figures, military and civilian, in styrene.
Andrea is a maker of individual kit figure, in resin, but with a great variety and not too expensive.
For conversions, look for Hornet, particularly for heads. You can get yourself some Tamiya figures and replace the heads with Hornet heads, and make some good conversions.
Verlinden is a good source, too, but now out of business, so you'll need to look on the second-hand market, with sources such as eBay, or vendor tables at model shows.
Those are some I think of, off the top of my head.